A.O2和O3 B.D和T C.CH3CH2CH2CH3和CH3CH(CH3)2D.CH3CH2CH2CH(C2H5)CH3和CH3CH2CH2CH(CH3)CH2CH3E. 和 F. 和CH2=CH﹣CH3G. 和
移动通信是利用电磁波传递信号的,电磁波在空中传播的速度为____ m/s.
A:You've tried on two skirts.
B:Sorry for taking up too much time of yours. But ______ of them looks nice on me.